Heteronuclear Cluster Compounds Research Articles

ChemInform Abstract: Structural and Bonding Patterns in Gold Clusters

AbstractReview: 85 refs.

ChemInform Abstract: The Heteronuclear Cluster Chemistry of the Group 1B Metals. Part 15. Effect of the Nature of the Group 1B Metals and the Cone Angles of the Attached Phosphine Ligands on the Metal Framework Structures of Heteronuclear Cluster Compound

Treatment of the salt [N(PPh3)2]2[Ru4(µ-H)2(CO)12] with 2 equivalents of the complex [M(NCMe)4]PF6 at –30 °C, followed by the addition of 2 equivalents of PR3, affords the hexanuclear cluster compounds [M2Ru4(µ3-H)2(CO)12(PR3)2][M = Cu, R = CHMe2, or C6H11(C6H11= cyclohexyl); M = Ag, R = CHMe2, C6H11 or CMe3] in ca. 50–65% yield. The analogous gold-containing species [Au2Ru4H2(CO)12(PR3)2](R = CHMe2, C6H11, or CMe3) were prepared in ca. 30–50% yield from the reaction of [N(PPh3)2]2[Ru4(µ-H)2(CO)12] with 2 equivalents of the compound [AuCl(PR3)], in the presence of TIPF6. Despite the relatively large size of the P(C6H11)3 ligand, the clusters [M2Ru4H2(CO)12{P(C6H11)3}2](M = Ag or Au) still adopt the capped trigonal-bipyramidal skeletal geometry, with the Group 1 B metals in close contact, which previous work has shown is preferred by clusters of general formula [M2Ru4H2(CO)12L2](M = Cu, Ag, or Au) when L is a smaller monodentate phosphine or phosphite ligand. However, the smaller size of the copper atom relative to silver and gold means that the P(C6H11)3 ligand is too bulky to allow two adjacent Cu{P(C6H11)3} fragments to be accommodated in the metal framework of [Cu2Ru4(µ3-H)2-(CO)12{P(C6H11)3}2]. Thus, the cluster is forced to adopt a sterically less-demanding skeletal geometry, which consists of a Ru4 tetrahedron with one edge bridged by a Cu{P(C6H11)3} unit and a non-adjacent face capped by the second such group. When the phosphine ligand P(CMe3)3, which is larger than P(C6H11)3, is attached to the Group 1 B metals in the clusters [M2Ru4(µ3-H)2-(CO)12{P(CMe3)3}2](M = Ag or Au), the silver- and gold-containing species are also forced to adopt a similar sterically less-demanding edge-bridged trigonal-bipyramidal metal core structure. In addition, the P(CMe3)3 ligand seems to be too bulky to allow a hexanuclear cluster of formula [Cu2Ru4H2(CO)12{P(CMe3)3}2] even to adopt an edge-bridged trigonal-bipyramidal metal framework structure and an attempt to prepare this species afforded the pentanuclear cluster [CuRu4(µ3-H)3-(CO)12{P(CMe3)3}] instead. The phosphine ligand P(CHMe2)3, which is smaller than P(C6H11)3, is not sufficiently bulky to cause the metal cores of [M2Ru4(µ3-H)2(CO)12{P(CHMe2)3}2](M = Cu, Ag, or Au) to change from the preferred capped trigonal-bipyramidal skeletal geometry in the solid state, but a second isomer of the copper-containing cluster, which probably has two face-capping Cu{P(CHMe2)3} units with no bonding interaction between them, is also present in solution at low temperatures. Variable-temperature 31P-{1H} and 1H n.m.r. spectroscopic studies demonstrate that the new Group 1 B metal heteronuclear cluster compounds undergo a variety of interesting dynamic processes in solution.

Reactivity of Transition Metal–Phosphorus Triple Bonds towards Triply Bonded [{CpMo(CO)2}2]: Formation of Heteronuclear Cluster Compounds

Thermolysis of [Cp*P{W(CO)5}2] (1) in the presence of [{CpMo(CO)2}2] leads to the novel complexes [{(CO)2Cp*W}{CpMo(CO)2}(micro,eta2:eta1:eta1-P2{W(CO)5}2)] (6; Cp=eta5-C5H5, Cp*=eta5-C5Me5), [{(micro-O)(CpMoWCp*)W(CO)4}{micro3-PW(CO)5}2] (7), [{CpMo(CO)2}2{Cp*W(CO)2}{micro3-PW(CO)5}] (8) and [{CpMo(CO)2}2{Cp*W(CO)2}(micro3-P)] (9). The structural framework of the main products 8 and 9 can be described as a tetrahedral Mo2WP unit that is formed by a cyclisation reaction of [{CpMo(CO)2}2] with an [Cp*(CO)2W[triple chemical bond]P-->W(CO)5] intermediate containing a W--P triple bond and subsequent metal-metal and metal-phosphorus bond formation. Photolysis of 1 in the presence of [{CpMo(CO)2}2] gives 8, 9 and phosphinidene complex [(micro3-PW(CO)5){CpMo(CO)2W(CO)5}] (10), in which the P atom is in a nearly trigonal-planar coordination environment formed by one {CpMo(CO)2} and two {W(CO)5} units. Comprehensive structural and spectroscopic data are given for the products. The reaction pathways are discussed for both activation procedures, and DFT calculations reveal the structures with minimum energy along the stepwise Cp* migration process under formation of the intermediate [Cp*(CO)2W[triple chemical bond]P-->W(CO)5].

ChemInform Abstract: Homonuclear and Heteronuclear Cluster Compounds of Gold

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Synthesis, crystal structures and dynamic behaviour of the pentanuclear mixed-metal cluster compounds [Au2Ru3(μ-H)(μ3-COMe){μ-Ph2P(CH2)nPPh2}(CO)9] (n =1 or 5) ‡

The cluster compound [Ru3(µ-H)3(µ3-COMe)(CO)9] reacted with the complex [Au2{µ-Ph2P(CH2)nPPh2}Me2] (n = 1 or 5) in diethyl ether solution to afford the new mixed-metal cluster compounds [Au2Ru3(µ-H)(µ3-COMe){µ-Ph2P(CH2)nPPh2}(CO)9] (n = 1 1 or 5 2) in ca. 30–40% yield. Compounds 1 and 2 have been characterized by IR and NMR spectroscopy and by single-crystal X-ray diffraction. The X-ray diffraction studies show that the Au2Ru3 metal cores of 1 and 2 both adopt similar distorted square-based pyramidal structures, with the basal plane defined by the two Au atoms and two of the Ru atoms and the third Ru atom forming the apex of the pyramid [Au–Au 2.878(1), Au–Ru 2.688(1)–2.863(1), Ru–Ru 2.887(1)–2.891(1) A for 1 and Au–Au 3.109(1), Au–Ru 2.716(3)–2.787(3), Ru–Ru 2.859(2)–2.895(3) A for 2]. The Ph2P(CH)nPPh2 (n = 1 or 5) ligand bridges the two Au atoms, the methoxycarbyne caps the Ru3 face and the hydride bridges the basal Ru–Ru edge of the metal framework. Each ruthenium atom is bonded to three terminal carbonyl groups. Variable-temperature NMR spectroscopic studies suggested that the metal skeletons of 1 and 2 are stereochemically non-rigid at high temperature in solution. The novel fluxional process is thought to involve a migration of the diphosphinedigold group around the three possible edge-bridging sites on the trigonal-planar triruthenium unit, together with a concomitant movement of the edge-bridging hydride ligand. Band-shape analysis of variable-temperature 1H and 13C-{1H} NMR spectra afforded values of ΔG ‡ for these proposed metal-core rearrangements of 67.1 ± 0.2 (1H) and 67.0 ± 0.2 kJ mol–1 (13C-{1H}) for 1 and 58.9 ± 0.1 kJ mol–1 (13C-{1H}) for 2. These free energies of activation are surprisingly high compared with those previously reported for skeletal rearrangements in gold–ruthenium heteronuclear cluster compounds.

Synthesis and structural characterization of two novel heteronuclear cluster compounds, [NEt 4] 4[WS 4Cu 5Br 7] and

The title compounds have been obtained by the reaction of [NH 4] 2(WS 4, CuBr, [NEt 4] 4Br and [Bu n 4N]Br in the solid state ( 1), or by the reaction of [NH 4] 2[WS 4], CuI and [Bu n 4N]I in the solid state and the pyridine substitution of the solid-state product in acetonitrile ( 2). X-ray diffraction analysis confirms that in the structure of 1 five of the six edges of the [WS 4] 2− tetrahedron are coordinated by CuBr units forming an open, double cubane-like structure, which possesses crystallographically imposed C 2 symmetry. The structure of 2, which possesses a crystallographic 4 symmetry axis situated at the tungsten atom, consists of a tetrahedral WS 4 core enveloped by an octahedral array of six copper atoms, forming a WS 4Cu 6 aggregate. Linked by Cu eqICu eq bridges, this aggregate connects with its nearest neighbours and develops a two-dimensional network. The substitution reactions of the solid-state product with pyridine are discussed.

The heteronuclear cluster chemistry of the Group IB metals. Part 16. Metal exchange reactions in Group IB metal heteronuclear cluster compounds. Synthesis and structural characterization of the trimetallic hexanuclear cluster compounds [MM′Ru4(µ3-H)2{µ-Ph2P(CH2)nPPh2}(CO)12](M = Cu, M′= Ag or Au; M = Ag, M′= Au; n= 1 or 2) and X-ray crystal structure of [AuCuRu4(µ3-H)2{µ-Ph2P(CH2)2PPh2}(CO)12

The heteronuclear cluster chemistry of the Group IB metals. Part 16. Metal exchange reactions in Group IB metal heteronuclear cluster compounds. Synthesis and structural characterization of the trimetallic hexanuclear cluster compounds [MM′Ru₄(µ₃-H)₂{µ-Ph₂P(CH₂)_nPPh₂}(CO)₁₂](M = Cu, M′= Ag or Au; M = Ag, M′= Au; n= 1 or 2) and X-ray crystal structure of [AuCuRu₄(µ₃-H)₂{µ-Ph₂P(CH₂)₂PPh₂}(CO)₁₂

High nuclearity clusters of the transition metals and a re-evaluation of the cluster surface analogy

In this paper, the structures and reactivities of homo- and hetero-nuclear gold cluster compounds are reviewed and related to the bonding models which have been developed for this class of compound. The present status of the cluster-surface analogy is then reviewed in a critical fashion in order tc highlight and emphasize the important similarities and differences.

High-resolution 31P-{ 1H} nuclear magnetic resonance studies of Group IB metal heteronuclear cluster compounds in the solid state

High-resolution 31P-{ 1H} NMR spectra of a series of crystalline mixed-metal cluster compounds containing M(PR 3) (M = Cu, Ag, or Au; R = alkyl or aryl) fragments have been recorded using magic angle sample spinning. The solid-state spectra are compared with those measured for the same compounds in solution and the values of the chemical shifts and, for the silver-containing species, the magnitudes of J( 107,109AgP) av, are generally very similar. The solid-state NMR spectra suggest that the dynamic processes involving hydrido ligand site-exchange or intermolecular exchange of PR 3 ligands between clusters, which have been previously observed at ambient temperature in solution for some of the clusters studied, do not occur or are not sufficiently rapid to be detected when the same compounds are in the crystalline state. In addition, the intramolecular metal core rearrangements, which all of the bimetallic clusters containing inequivalent M(PR 3) fragments undergo at ambient temperature in solution, are also not observed by solid-state NMR spectroscopy in the crystalline compounds. For some of the clusters of this latter class, the solid-state spectra can provide useful structural information about the ground-state metal framework geometries which it is impossible to obtain from solution studies, even at low temperatures.

The heteronuclear cluster chemistry of the Group IB metals XIV. The influence of the P(CH 2Ph) 3 ligand on the metal framework structures adopted by mixed-metal clusters containing M{P(CH 2Ph) 3} (M  Cu or Ag) fragments. Crystal structures of [Cu 2Ru 4(μ 3-H) 2(CO) 12{μ-P(CH 2Ph) 2-(η 2-CH 2Ph)}] and [Cu 2Ru 4(μ 3-H) 2(CO) 12{P(CH 2Ph) 3} 2

Treatment of a dichloromethane solution of the salt [N(PPh 3) 2] 2[Ru 4(μ-H) 2(CO) 12] with two equivalents of the complex [M(NCMe) 4]PF 6 (M  Cu or Ag) at −30°C, followed by the addition of two equivalents of P(CH 2Ph) 3, affords the novel mixed-metal cluster compound [Cu 2Ru 4(μ 3-H) 2(CO) 12{μ-P(CH 2Ph) 2(η 2-CH 2Ph)}] (77% yield) when M  Cu, whereas the expected product, [Ag 2Ru 4(μ 3-H) 2(CO) 12{P(CH 2Ph) 3} 2] (37% yield), is obtained for M  Ag. When an acetone solution of [N(PPh 3) 2] 2[Ru 4(μ-H) 2(CO) 12] is treated with a dichloromethane solution containing two equivalents of the compound [CuCl{P(CH 2Ph) 3}], in the presence of TlPF 6, a mixture of [Cu 2Ru 4(μ 3-H) 2(CO) 12{μ-P(CH 2Ph) 2(η 2-CH 2Ph)}] (44% yield) and [Cu 2Ru 4(μ 3-H) 2(CO) 12{P(CH 2Ph) 3} 2] (12% yield) is produced. Single-crystal X-ray diffraction studies were performed on [Cu 2Ru 4(μ 3-H) 2(CO) 12 {μ-P(CH 2Ph) 2(η 2-CH 2Ph)}] and [Cu 2Ru 4(μ 3-H) 2(CO) 12{P(CH 2Ph) 3} 2]. The former cluster exhibits a capped trigonal bipyramidal metal framework structure (CuCu 2.532(2), CuRu 2.585(2)–2.813(1), RuRu 2.790(1)–2.981(1) Å) and the single P(CH 2Ph) 3 group adopts a novel bidentate bonding mode by bridging the two adjacent copper atoms via bonds from its phosphorus atom (CuP 2.199(2) Å) and an η 2-CH 2Ph ring (CuC 2.146(10) and 2.339(12) Å). In marked contrast, [Cu 2Ru 4(μ 3-H) 2(CO) 12{P(CH 2Ph) 3} 2] adopts an unusual metal core structure, which consists of a Ru 4 tetrahedron with one edge bridged by a Cu{P(CH 2Ph) 3} unit and a non-adjacent face capped by the second Cu{P(CH 2Ph) 3} group (CuRu 2.589(4)–2.724(4), RuRu 2.760(3)–2.984(4) Å). Infrared and NMR spectroscopic data show that [Ag 2Ru 4(μ 3-H) 2(CO) 12{P(CH 2Ph) 3} 2] exhibits a capped trigonal bipyramidal skeletal geometry, with the silver atoms in close contact. Thus, although the P(CH 2Ph) 3 ligand is evidently too bulky to allow two adjacent Cu{P(CH 2Ph) 3} units to be accommodated in the metal skeleton of [Cu 2Ru 4(μ 3-H) 2(CO) 12{P(CH 2Ph) 3} 2], the greater size of the silver atom relative to copper means that the analogous silver-containing species can adopt the metal framework structure which previous work suggests is preferred by clusters of this type. Variable-temperature 31P-{ 1H} and 1H NMR spectroscopic studies demonstrate that all three of the new heteronuclear cluster compounds undergo a number of interesting dynamic processes in solution.

ChemInform Abstract: Heteronuclear Cluster Chemistry of Copper, Silver, and Gold

Publisher Summary This chapter reviews the synthesis, structures, chemical properties, and dynamic behavior of copper, silver, and gold—containing heteronuclear cluster compounds. A cluster compound is considered to be a species, which contains three or more framework atoms with sufficient interactions among them to define either a metal core made up of one or more trigonal planar M 3 units or a three-dimensional skeletal geometry based on a wide variety of polyhedra. The chapter is restricted Group IB metal cluster compounds in which the skeletal atoms consist predominantly of transition metals. In the vast majority of the Group IB metal heteronuclear clusters reported so far, one two-electron donor ligand is attached to each coinage metal and PR 3 is the most common ligand of this type. A number of species with coinage metals that do not carry any ligands or with ligands that are not simple two-electron donors bonded to the Group IB metals are also known and these clusters are also described in this chapter.

The heteronuclear cluster chemistry of the Group 1B metals. Part 15. Effect of the nature of the Group 1B metals and the cone angles of the attached phosphine ligands on the metal framework structures of heteronuclear cluster compounds. Synthesis, structures, and dynamic behaviour of the bimetallic hexanuclear cluster compounds [M2Ru4H2(CO)12(PR3)2](M = Cu, R = CHMe2 or C6H11; M = Ag

Treatment of the salt [N(PPh3)2]2[Ru4(µ-H)2(CO)12] with 2 equivalents of the complex [M(NCMe)4]PF6 at –30 °C, followed by the addition of 2 equivalents of PR3, affords the hexanuclear cluster compounds [M2Ru4(µ3-H)2(CO)12(PR3)2][M = Cu, R = CHMe2, or C6H11(C6H11= cyclohexyl); M = Ag, R = CHMe2, C6H11 or CMe3] in ca. 50–65% yield. The analogous gold-containing species [Au2Ru4H2(CO)12(PR3)2](R = CHMe2, C6H11, or CMe3) were prepared in ca. 30–50% yield from the reaction of [N(PPh3)2]2[Ru4(µ-H)2(CO)12] with 2 equivalents of the compound [AuCl(PR3)], in the presence of TIPF6. Despite the relatively large size of the P(C6H11)3 ligand, the clusters [M2Ru4H2(CO)12{P(C6H11)3}2](M = Ag or Au) still adopt the capped trigonal-bipyramidal skeletal geometry, with the Group 1 B metals in close contact, which previous work has shown is preferred by clusters of general formula [M2Ru4H2(CO)12L2](M = Cu, Ag, or Au) when L is a smaller monodentate phosphine or phosphite ligand. However, the smaller size of the copper atom relative to silver and gold means that the P(C6H11)3 ligand is too bulky to allow two adjacent Cu{P(C6H11)3} fragments to be accommodated in the metal framework of [Cu2Ru4(µ3-H)2-(CO)12{P(C6H11)3}2]. Thus, the cluster is forced to adopt a sterically less-demanding skeletal geometry, which consists of a Ru4 tetrahedron with one edge bridged by a Cu{P(C6H11)3} unit and a non-adjacent face capped by the second such group. When the phosphine ligand P(CMe3)3, which is larger than P(C6H11)3, is attached to the Group 1 B metals in the clusters [M2Ru4(µ3-H)2-(CO)12{P(CMe3)3}2](M = Ag or Au), the silver- and gold-containing species are also forced to adopt a similar sterically less-demanding edge-bridged trigonal-bipyramidal metal core structure. In addition, the P(CMe3)3 ligand seems to be too bulky to allow a hexanuclear cluster of formula [Cu2Ru4H2(CO)12{P(CMe3)3}2] even to adopt an edge-bridged trigonal-bipyramidal metal framework structure and an attempt to prepare this species afforded the pentanuclear cluster [CuRu4(µ3-H)3-(CO)12{P(CMe3)3}] instead. The phosphine ligand P(CHMe2)3, which is smaller than P(C6H11)3, is not sufficiently bulky to cause the metal cores of [M2Ru4(µ3-H)2(CO)12{P(CHMe2)3}2](M = Cu, Ag, or Au) to change from the preferred capped trigonal-bipyramidal skeletal geometry in the solid state, but a second isomer of the copper-containing cluster, which probably has two face-capping Cu{P(CHMe2)3} units with no bonding interaction between them, is also present in solution at low temperatures. Variable-temperature 31P-{1H} and 1H n.m.r. spectroscopic studies demonstrate that the new Group 1 B metal heteronuclear cluster compounds undergo a variety of interesting dynamic processes in solution.

The synthesis of heteronuclear cluster compounds containing M(PR 3) (M = Cu, Ag, or Au; R = alkyl or aryl) units via Group IB metal exchange reactions

Treatment of dichloromethane solutions of the heteronuclear cluster compounds [M 2Ru 4(μ 3-H) 2{μ-Ph 2P(CH 2) 2PPh 2}(CO) 12] (M = Cu or Ag) with dichloromethane solutions containing the appropriate quantities of the complex [Ag(NCMe) 4]PF 6 or [AuCl(SC 4H 8)] results in the replacement of either one or both of the Group IB metals M by silver or gold atoms. The products from the Group IB metal exchange reactions are obtained in ca. 65–75% yield.

The heteronuclear cluster chemistry of the Group 1 B metals. Part 12. Variable temperature nuclear magnetic resonance spectroscopic studies of the dynamic behaviour of the mixed-metal cluster compounds [M2Ru4(µ3-H)2(µ-L)(CO)12][M = Cu or Ag, L = Ph2P(CH2)nPPh2(n= 1–6) or cis-Ph2PCHCHPPh2; M = Cu, L = Ph2As (CH2)nPPh2(n= 1 or 2)] in solution

The free energies of activation (ΔG‡) for the intramolecular metal core rearrangements which the clusters [M2Ru4(µ3-H)2(µ-L)(CO)12][M = Cu or Ag, L = Ph2P(CH2)nPPh2(n= 1–6); M = Cu, L = Ph2 As (CH2)nPPh2(n= 1 or 2)] undergo in solution have been calculated by bandshape analysis of variable temperature 31P-{1H} or 1H n.m.r. spectra or estimated from the coalescence temperature in 31P-{1H} n.m.r. spectra. Changes in the nature of the bidentate ligands attached to the coinage metals cause relatively large alterations of up to ca. 13 and ca. 1O kJ mol–1 in the values of ΔG‡ for the copper- and silver-containing species, respectively. The formal replacement of two PPh3 groups in [Ag2Ru4(µ3-H)2(CO)12(PPh3)2] by a Ph2PCH2PPh2 or Ph2P(CH2)2PPh2 ligand reduces the value of ΔG‡ by ca. 8 and ca. 4 kJ mol–1, respectively. These decreases, together with the previously reported distortions in metal framework geometry from capped trigonal bipyramidal to or towards capped square-based pyramidal, which occur for the same formal change of ligands in the analogous gold-containing species, provide some indirect evidence to support a restricted Berry pseudo-rotation mechanism for the Group 1 B metal site-exchange process in the clusters studied. The new heteronuclear cluster compounds [M2Ru4H2(µ-cis- Ph2PCHCHPPh2)(CO)12][M = Cu (2O), Ag (21), or Au (22)] have been synthesized and the effect of the cis-Ph2PCHCHPPh2 ligand on the value of ΔG‡ for the metal core rearrangement of (21) and on the skeletal geometry adopted by (22) is also consistent with the restricted Berry pseudorotation mechanism. The magnitude of ΔG‡ for the silver-containing species (21) is ca. 7 kJ mol–1 lower than that for the analogous PPh3-ligated cluster and the metal framework geometry of the gold-containing compound (22) is altered from capped trigonal bipyramidal to capped squarebased pyramidal when two PPh3 groups are formally replaced by the cis-Ph2PCHCHPPh2 ligand. In addition, variable temperature 1H and 31P-{1H} n.m.r. spectroscopic studies show that the hydrido ligands in the copper and silver clusters containing Ph2E(CH2)nPPh2(E = P, n= 1–6; E = As, n= 1 or 2) are rendered equivalent by dynamic behaviour which involves conformational changes in the methylene backbones of the bidentate ligands and that the cis-Ph2PCHCHPPh2 ligand in (21) undergoes a novel fluxional process involving intramolecular site exchange of the two phosphorus atoms between the two silver atoms.

Effect of the phosphine ligand cone angle on the metal frameworks of heteronuclear cluster compounds containing Cu(PR3)(R = alkyl or aryl) groups: X-ray structure analyses of [Cu2Ru4(µ3-H)2(CO)12(PR3)2](R = cyclo-C6H11or CHMe2)

The cone angle of the phosphine ligands in the heteronuclear cluster compounds [Cu2Ru4(µ3-H)2(CO)12(PR3)2](R = alkyl or aryl) has a marked effect on the metal framework structure adopted; when R = CHMe2, two skeletal isomers, which interconvert at ambient temperature, are present in solution and when R = cyclo-C6H11, the cluster exhibits a previously unobserved type of Cu2Ru4 metal core structure.

Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 83. Molybdenum and tungsten complexes containing the alkylidyne group C{η6-C6H4(OMe-2)Cr(CO)3}

The alkylidyne-metal complexes [CrM{µ-σ:η6-CC6H4(OMe-2)}(O2CCF3)(CO)5L2][M = Mo or W, L2= tmen (Me2NCH2CH2NMe2) or bipy (2,2′-bipyridine)] and [CrM{µ-σ:η6-CC6H4(OMe-2)}(CO)5L]{M = Mo, L =η-C5H5 or HB(pz)3[hydrotris(pyrazol-1-yl)borate]; M = W, L =η-C5H5} have been prepared. In these species the alkylidyne ligand attached to Mo or W is η6-co-ordinated to a Cr(CO)3 group. Several reactions of the complexes [CrM{µ-σ:η6-CC6H4(OMe-2)}(CO)5(η-C5H5)] with low-valent metal compounds have been studied. These have led to the isolation of various heteronuclear metal cluster compounds with bonds between molybdenum or tungsten and platinum, nickel, cobalt, and rhodium. The n.m.r. data for the new products are reported and discussed in relation to the structures proposed.

ChemInform Abstract: The Characterization and Catalytic Applications of Heteronuclear Cluster Compounds of Iron, Ruthenium and Osmium

ChemInform Abstract: The Characterization and Catalytic Applications of Heteronuclear Cluster Compounds of Iron, Ruthenium and Osmium

Bismuth–cobalt heteronuclear carbonyl cluster compounds. Synthesis and X-ray characterization of the neutral [BiCo3(CO)9] and of the paramagnetic anion [Bi2Co4(CO)11]–

Reactions between BiCl3 and the anion [Co(CO)4]– under various conditions afford some new products: the anion [Bi{Co(CO)4}4]–, the neutral tetrahedral cluster [BiCo3(CO)9], and the paramagnetic cluster [Bi2Co4(CO)11]– containing a Bi2Co4 array formed by three face-to-face condensed tetrahedral units.

Group IB metal exchange reactions: A novel, high yield route to heteronuclear cluster compounds containing M(PPh 3) (M = Cu, Ag or Au) moieties

Either one or both (except when M′ = Cu) of the M(PPh 3) (M = Cu, Ag or Au) moieties in the heteronuclear metal cluster compounds [M 2Ru 4(μ 3-H) 2(CO) 12(PPh 3) 2] can be replaced by similar units, containing a different Group Ib metal M′, by treating dichloromethane solutions of the clusters with the appropriate amounts of the complexes [M′X(PPh 3)] (M′ = Cu or Au, X = Cl; M′ = Ag, X = I), in the presence of TIPF 6; the new clusters are obtained in ca. 70–80% yield.

Heteronuclear cluster compounds

Several designed syntheses have been developed for heteronuclear organometallic cluster compounds. They involve step-by-step construction, fragment combination and metal exchange. The compounds obtained permit the study of the physical phenomena of electron distribution and chirality in the cluster frameworks. Prominent chemical phenomena are the weakness of some metal-metal bonds, the unsaturated nature of some clusters, and polarity due to heteronuclearity. They permit the study of basic cluster reactions like the unfolding of the clusters with nucleophiles, the addition of substrates without gross changes in the cluster framework and without ligand substitution, the capping of clusters by suitable ligands, and the reaction of different substrates at different locations in the cluster core.